Navigation Systems are broadly used in various fields such as ships and vehicles, because they can sense the position of a moving body and show it on a display in real time.
Presumably, the navigation systems will spread increasingly for they can sense accurately the position of a moving body utilizing radio waves from Global Positioning System satellites, and with the technical developments of liquid crystal displays as well as the cost and size reduction of integrated circuits.
The conventional navigation systems provide an excellent navigation for showing the positions of a moving body, but do not accommodate navigation data for receiving broadcast waves and selecting broadcast stations.
For example, a vehicle includes a broadcast wave receiver such as a TV set or radio set to create a pleasant atmosphere. Particularly, vehicles on which the navigation systems are mounted often include TV sets.
Supposing that a vehicle is moving on an expressway surrounded by many mountains from a point A (e.g. Tokyo City) to another point B (e.g. Matsumoto City). The driver decides to take a break at a service area, and to watch TV in the vehicle. Being unfamiliar with the area, he is unaware of which TV broadcasts are receivable through which TV channels as it is often the case that different channels transmit different broadcasts for every geographic area. Thus, the driver would have to change the channels and find the receivable TV broadcasts in vain, making the TV station selection complicated.
Furthermore, assuming that a sightseeing bus including a TV set is moving while the television is on. Frequently, TV broadcast reception gradually degrades and in worst cases, the TV broadcast becomes invisible. For example, the nation-wide TV broadcast waves from Japan Broadcasting Corporation (NHK) may be received through different channels in different areas. Therefore, if a vehicle is moving while the NHK TV broadcast is on, the TV broadcast wave reception may gradually degrade and the images may become invisible. In such a case, if the TV channels are automatically switched depending on the area in which the vehicle is moving, the TV broadcasts may be transmitted in a desired condition. However, the prior art does not provide such a TV broadcast receiver.
In view of such problems in the prior art, an object of the present invention is to provide an improved broadcast station data detector and broadcast receiver for a moving body, which can utilize the positional data of the moving body to know a receivable broadcast station at the position of the moving body in real time, whereby even a user unfamiliar with the area can smoothly select the receivable broadcast station.
Another object of the present invention is to provide a broadcast receiver which can utilize the positional data of the moving body to switch the channels automatically and to obtain a desired broadcast reception.